In the ideal case of a human being standing in the correct erect position, the vertical line which passes through the centre of gravity of the body should meet the support surface on the ground at a point defined by the intersection, in the support plane, of a segment in the sagittal direction arranged equidistant from the two feet and a segment in the transverse direction which passes about halfway between the tibiotarsal articulation and the metatarso-phalangeal articulation of the two feet. In this condition, the load is equally distributed between the two feet and between the front contact zone and the rear contact zone of the foot.
The postural defects result in displacement of the contact pressure points and the barycentre forwards or backwards and/or to the right or left, such that they move away from their optimum position.
It is therefore useful to be able to define using instruments with a suitable precision both the deviations from the optimal positions and the effects of the postural corrections applied in order to try to reduce the deviations determined.
Attempts at performing measurements using instruments have been made in the prior art, but the results were not regarded as being satisfactory and complete.
Moreover, it is a widespread belief that a difference in the level of the iliac crests is an indication of an different length of the lower limbs. In reality, the difference in level may be caused by an anteversion of an iliac wing which rotates and flexes further forwards than the other wing. The correction by means of raising of the leg which appears to be shorter therefore results only in an apparent correction of the defect, giving rise to various postural complications.